3.3. Abnormal Accumulation of mtROS is Involved in VSMC-Derived Foam Cell Necroptosis
Phosphorylation of RIP1 and RIP3 is necessary for necroptosis activation. Han et al. reported that mtROS promoted RIP1 autophosphorylation and were essential for RIP3 recruitment into the necrosomes [9]. Other studies have illustrated that the mitochondrial permeability transition pore (mPTP) opening is essential for RIP3-mediated necroptosis [13,14], as it is a consequence of mitochondrial potential collapse. To elucidate the mechanism underlying ox-LDL-induced VSMC-derived foam cell necroptosis, we incubated VSMCs with an ROS scavenger, Tempol, before treatment with ox-LDL. After incubation with Tempol, the generation of mtROS induced by ox-LDL in VSMC-derived foam cells was reduced (Fig. 3a) and the loss of ΔΨm was also effectively inhibited (Fig. 3b). To further characterize the effect of Tempol on ox-LDL-induced cell necroptosis, the PI-positive cells were examined using flow cytometry. Following pre-incubation with Tempol, the number of ox-LDL-induced PI-positive cells was significantly reduced (Fig. 3c). These results suggest abnormal accumulation of mtROS as a potential mechanism underlying ox-LDL-induced cell necroptosis.